The present invention relates to improved syntheses of known and novel benzothiazine dioxide which are potent and selective endothelin antagonists. The processes of the instant invention are improved over those recited in U.S. Pat. No. 5,599,811 which is hereby incorporated by reference.
The compounds of the instant invention exhibit very significant improvements over those described in U.S. Pat. No. 5,599,811. These improvements include: binding affinity to the ET.sub.A receptor, ET.sub.A selectivity, functional activity, long pharmacokinetic half-life, high bioavailability, in vivo activity in inhibiting the pressor effect caused by bET-1, oral activity with relatively long duration of action, and efficacy in acute hypoxic pulmonary hypertension in rats.
The processes of the instant invention provide more facile syntheses with higher yields. They are short, clean, reproducible and no tedious chromatography is needed. Moreover, the processes are scaleable and therefore useful for large-scale development.
The present invention also relates to antagonists of endothelin useful as pharmaceutical agents, to pharmaceutical compositions which include these compounds and a pharmaceutically acceptable carrier, and to pharmaceutical methods of treatment. More particularly, the compounds of the present invention are antagonists of endothelin useful in treating elevated levels of endothelin, acute and chronic renal failure, essential renovascular malignant and pulmonary hypertension, cerebral infarction and cerebral ischemia, cerebral vasospasm, cirrhosis, septic shock, congestive heart failure, endotoxic shock, subarachnoid hemorrhage, arrhythmias, asthma, preeclampsia, atherosclerotic disorders including Raynaud's disease and restenosis, angina, cancer, benign prostatic hyperplasia, ischemic disease, gastric mucosal damage, hemorrhagic shock, ischemic bowel disease, and diabetes.
Also, the compounds will be useful in cerebral ischemia or cerebral infarction resulting from a range of conditions such as thromboembolic or hemorrhagic stroke, cerebral vasospasm, head injury, hypoglycemia, cardiac arrest, status epilepticus, perinatal asphyxia, anoxia such as from drowning, pulmonary surgery, and cerebral trauma.